Body of traditional social and legal custom and practice that constitutes proper observance of Islam. Early Muslims did not concur on what constituted sunna, because of the wide variety of pre-Islamic practices among converted peoples that had to be assimilated, reconciled, or abandoned. In the 8th century the sunna of Muhammad, as preserved in eyewitness records, was codified as the Hadith by Abu 'Abd Allah Shaf'ii. Later Muslim scholars strengthened the authority of sunna by devising a system for attesting the authenticity of various practices claimed as descending from Muhammad. See also'ilm al-hadith; isnad; Shari'ah; tafsir.